Bending device

ABSTRACT

A bending device for use in an endoscope, a catheter or the like is of a simple construction having a coil, an operating wire and a pair of limitation members for limiting an axial compression of the coil. The pair of limitation members are arranged along the length of the coil, and are mounted respectively on diametrically-opposite portions of the coil. The coil is bendable in a direction perpendicular to a plane in which the pair of limitation members are disposed. Instead of the coil, a bellows can be used.

This application is a division of U.S. application Ser. No. 08/037,559filed Mar. 26, 1993, now U.S. Pat. No. 5,363,882, which is a division ofU.S. application Ser. No. 07/594,118 filed Oct. 9, 1990, now U.S. Pat.No. 5,203,380.

BACKGROUND OF THE INVENTION

This invention relates to a bending device for use, for example, in anendoscope.

As is well known, an endoscope comprises a hollow body, a flexibleinsertion portion extending from a front end of the body, a flexiblebending portion extending from a distal end of the insertion portion,and a rigid portion provided at a distal end of the bending portion. Aninspection window and an illumination window are formed at the rigidportion.

Japanese Utility Model Publication No. 9274/77 discloses a flexible tubestructure for an endoscope which structure has one coil and a resilientthin plate. FIG. 1 of Japanese Laid-Open (Kokai) Utility ModelApplication No. 10605/80 shows an example in which this flexible tubestructure is applied to a bending portion of an endoscope. Morespecifically, in the bending portion, the resilient thin plate isreceived in an internal space defined by the coil and extends in thelongitudinal direction of the coil. Recesses are formed in each ofopposite lateral edges of the resilient thin plate, and are juxtaposedin the longitudinal direction of this plate. The turn portions of thecoil are engaged in the recesses. The bending portion is bent in adirection perpendicular to the plane of the resilient thin plate by anoperating wire, so as to direct an inspection window and an illuminationwindow of the rigid portion toward a desired direction.

The above resilient thin plate performs two functions. The firstfunction is to prevent the coil from being axially compressed whenpulling the operating wire, thereby ensuring a proper bending of thebending portion. The second function is to limit the direction ofbending of the bending portion to a direction perpendicular to the planeof the resilient thin plate.

The above bending portion is simple in construction, and can be easilymanufactured. However, since the resilient thin plate is received in theinternal space of the coil in such a manner that this plate divides theinternal space into two space portions, the resilient thin plate isobstructive when optical fiber bundles, guide tubes and etc., are to beinserted into the internal space. As a result, considerable limitationsare imposed on the thicknesses or diameters of the optical fiber bundlesand the guide tubes. Moreover, a dead space tends to be present in thetwo space portions, thus failing to make effective use of the internalspace.

Referring to another prior art, Japanese Laid-Open Utility ModelApplication No. 110443/77 discloses a fiber scope including a bellowswhich is not designed to be bent by an operating wire.

SUMMARY OF THE INVENTION

An object of the invention is to provide a bending device which issimple in construction because of the use of a bellows, and can be bentby pulling an operating wire, and enables an internal space of thebellows to be used effectively.

The above object has been achieved by a bending device comprising:

(a) a bellows having an internal space therein, and having a corrugatedperipheral wall defined by first and second portions arrangedalternately in a direction of an axis of the bellows, the first portionsbeing bulged radially outwardly whereas the second portions are bulgedradially inwardly;

(b) operating wire means for bending the bellows, the operating wiremeans having a proximal end portion adapted to receive an operatingforce, the operating wire means having a distal end portionsubstantially fixed to a distal end portion of the bellows; and

(c) at least one pair of independent limitation means for limiting anaxial compression of the bellows, the pair of limitation means beingarranged in an axial direction of the coil and mounted respectively ondiametrically-opposite portions of the peripheral wall of the bellows,each of the pair of limitation means including insertion portions fittedrespectively in at least one of the first portions and second portionsof the bellows, and the bellows being bendable in a directionperpendicular to a plane in which the pair of limitation means aredisposed;

wherein each of the limitation means includes a row of alternate firstand second pieces serving as the insertion portions, the first piecesbeing disposed inside the peripheral wall of the bellows, the secondpieces being disposed outside the peripheral wall of the bellows, thefirst pieces being fitted in and fixedly secured to the first portionsof the bellows, respectively, and the second pieces being fitted in andfixedly secured to the second portions of the bellows, respectively.

The object of the invention has also been achieved by a bending devicecomprising elements (a), (b), and (c) as set forth above wherein a rowof insertion holes are formed through the corrugations of the peripheralwall of the bellows, the row of insertion holes being disposed on astraight line parallel to the axis of the bellows, and the operatingwire means being passed through the row of insertion holes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an endoscope incorporating a bendingportion according to the present invention;

FIG. 2 is an enlarged, front-elevational view showing an internalstructure of the bending portion;

FIG. 3 is an enlarged, plan view showing the internal structure of thebending portion:

FIG. 4 is a cross-sectional view taken along the line IV--IV of FIG. 2;

FIG. 5 is an enlarged, fragmentary view showing a condition ofengagement between a coil and a strip;

FIG. 6 is a cross-sectional view of portions of the coil and the stripin a bent condition of the bending portion;

FIGS. 7 and 8 are views similar to FIG. 5, but showing modified bendingportions, respectively;

FIGS. 9 and 10 are perspective views showing internal structures offurther modified bending portions, respectively;

FIG. 11 is a cross-sectional view of a further modified bending portion;

FIG. 12 is a cross-sectional view taken along the line XII--XII of FIG.11;

FIG. 13 is a cross-sectional view taken along the line XIII--XIII ofFIG. 11;

FIG. 14 is a view similar to FIG. 11, but showing a further modifiedform of the invention;

FIG. 15 is a cross-sectional view taken along the line XV--XV of FIG.14;

FIG. 16 is a cross-sectional view taken along the line XVI--XVI of FIG.14;

FIG. 17 is a view similar to FIG. 11, but showing a further modifiedform of the invention;

FIG. 18 is a cross-sectional view taken along the line XVIII--XVIII ofFIG. 17;

FIG. 19 is a view similar to FIG. 11, but showing a further modifiedform of the invention;

FIG. 20 is a cross-sectional view taken along the line XX--XX of FIG.19; and

FIG. 21 is a view similar to FIG. 20, but showing a further modifiedform of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

A preferred embodiment of the invention will now be described withreference to the drawings.

An endoscope shown in FIG. 1 comprises a hollow body 10, an insertionportion 20 extending from a front end of the body 10, a bending portion(bending device) 30 extending from a distal end of the insertion portion20, and a rigid portion 40 provided at a distal end of the bendingportion 30. Each of the insertion portion 20 and the bending portion 30has a tubular shape, and is so flexible as to be bent.

An ocular tube 11 is mounted on the proximal end of the body 10, and amanipulation dial 12 is mounted on the peripheral wall of the body 10,and a forceps inlet portion 13 is formed on the peripheral wall of thebody 10. A cable (not shown) is fixedly secured at one end to theperipheral wall of the body 10, and a connector (not shown) to beconnected to a light source device is mounted on the other end of thiscable.

As shown in FIG. 2, the rigid portion 40 comprises a frame 41. The frame41 has a base portion 41a of a circular cross-section, and a cylindricalportion 41b extending from the base portion 41a toward the bendingportion 30. An inspection window, an illumination window, a forcepsoutlet and etc., are provided at the base portion 41a. The ocular tube11 is optically connected to the inspection window via an imagetransmitting system (not shown) including an optical fiber bundlepassing through the body 10, the insertion portion 20 and the bendingportion 30. With this arrangement, inspection from the ocular tube 11can be made. Illumination light from the light source device is appliedto the illumination window via an optical fiber bundle passing throughthe above connector, the above cable, the body 10, the insertion portion20 and the bending portion 30. The forceps outlet is connected to theforceps inlet portion 13 via a guide tube (not shown) passing throughthe body 10, the insertion portion 20 and the bending portion 30.

The insertion portion 20 includes a holder coil (not shown) made from astrip or elongated narrow plate. A proximal end of this holder coil isfixedly secured to the body 10, and the distal end of the holder coil isconnected to a connecting tube (not shown). A braid tube (not shown) isfitted on the holder coil, and a tube 22 (shown only in FIG. 1) made ofa resin or rubber is fitted on the braid tube.

The internal structure of the bending portion 30 will now be describedin detail with reference to FIGS. 2 to 6. The bending portion 30includes a coil 31. The coil 31 has a number of turn portions 31a eachhaving a circular or round shape as viewed in the axial direction of thecoil 31 as shown in FIG. 4. The turn portion 31a are juxtaposed in theaxial direction of the coil 31. The proximal end of the coil 31 isfixedly secured to the above-mentioned connecting tube, and is connectedto the distal end of the holder coil of the insertion portion 20 viathis connecting tube. The distal end of the coil 31 is fixedly securedto the outer peripheral surface of the cylindrical portion 41b of theframe 41 of the rigid portion 40. The coil 31 has an internal space 32therein, and the above-mentioned optical fiber bundles and guide tubeare received in the internal space 32.

A pair of strips or band-like plates (limiting members) 33 are mountedrespectively on diametrically-opposite portions (i.e., portionsdiametrically opposite right and left in FIG. 4) of the outer peripheryof the coil 31. Each strip 33 is made of metal, and is relatively thin,and has a narrow width. Each strip 33 extends in the longitudinaldirection of the coil 31 over the entire length thereof. As best shownin FIG. 5, the strip 33 is formed or bent into a corrugated shape, andhas a number of support portions 33a of a generally semicircularcross-section spaced at equal intervals from one another along thelength of the strip 33. The semi-circular support portion 33a has aninner diameter slightly greater than the transverse cross-section of theturn portion 31a of the coil 31. Each adjacent support portions 33a areinterconnected by a connecting portion 33b. The outside section of eachturn portion 31a of the coil 31 is received in a respective one of thesupport portions 33a of each strip 33 over about a half of thecross-section of the turn portion 31a. The support portions 33a of thestrip 33 are fixedly secured respectively to the turn portions 31a ofthe coil 31 by spot welding at regions indicated by reference characterA in FIG. 5. With this construction, the turn portions 31a of the coil31 are arranged at equal intervals in the axial direction of the coil31. The strip plates 33 may be fixed to the coil 31 by an elasticadhesive or by brazing.

A braid tube, softer than the braid tube of the insertion portion 20, isfitted on the outer periphery of the coil 31, and a tube 34 (only shownin FIG. 1), softer than the tube 22 of the insertion portion 20, isfitted on the outer periphery of this braid tube.

Next, a mechanism for bending the bending portion 30 will now bedescribed. This mechanism includes two operating wires 51 and 52. Theoperating wires 51 and 52 are fixedly secured to a peripheral surface ofa pulley 50 mounted within the body 10, and extend forwardly from theupper and lower portions of the pulley 50, respectively. The pulley 50is connected to the manipulation dial 12 via a shaft (not shown)extending through the peripheral wall of the body 10.

In the insertion portion 20, the operating wires 51 and 52 are passedrespectively through a pair of guide tubes of a small diameter. Each ofthese guide tubes is formed by spirally winding a wire, and is receivedwithin the holder coil. The proximal ends of the guide coils are fixedlysecured respectively to diametrically-opposite portions of the body 10(that is, opposed upper and lower portions of the body 10 in FIG. 1),and the distal ends of the guide coils are fixedly secured respectivelyto diametrically-opposite upper and lower portions of the innerperipheral surface of the above-mentioned connecting tube.

The operating wires 51 and 52 are passed through the internal space 32of the coil 31, and are fixedly secured at their distal endsrespectively to diametrically-opposite upper and lower portions (FIGS. 1and 2) of the cylindrical portion 41b of the frame 41 of the rigidportion 40 by brazing. The positions of fixing of the distal ends of theoperating wires 51 and 52, as well as the positions of fixing of thedistal ends of the above guide coils, are circumferentially spaced 90°from the pair of strips 33.

The connecting portions 33b of the strips 33 have a relatively highrigidity to withstand a compressive force exerted in the longitudinaldirection of the coil 31 upon pulling of the operating wire 51 or 52.Therefore, those sections of the turn portions 31a of the coil 31engaged with each strip 33 are maintained at substantially constantintervals. As a result, the coil 31 and hence the bending portion 30 cannot be bent in a direction X indicated in FIG. 4, and can be bent onlyin a direction Y in FIG. 4 (i.e., upward-downward direction in FIG. 1).

In the above construction, when the manipulating dial 12 is angularlymoved in a counterclockwise direction (FIG. 1), the operating wire 52 ispulled, and the operating wire 51 is loosened. At this time, since theaxial compression of the coil 31 is limited by the strips 33, thepulling force applied by the operating wire 52 is effectively utilizedto bend the coil 31 and hence the bending portion 30. More specifically,as shown in FIG. 6, the distance between those sections of the adjacentturn portions 31a engaged with each strip 33 remain unchanged, and thedistance between the upper sections of the adjacent turn portions 31aincreases whereas the distance between the lower sections of theadjacent turn portions 31a decreases. As a result, the bending portion30 is bent downward.

In contrast, when the manipulating dial 12 is angularly moved in aclockwise direction, the operating wire 51 is pulled, and the operatingwire 52 is loosened. As a result, the bending portion 30 is bent upward.

During the bending of the bending portion 30, the strips 33 will notaffect or obstruct this bending. The reason for this is that because ofthe corrugated configuration of each strip 33, one lateral edge portionof the strip 33 is resiliently contracted whereas the other lateral edgeportion is resiliently expanded, so that the strip 33 is bent in thedirection of the width thereof, as shown in FIG. 6.

During the bending of the bending portion 30, the turn portions 31a ofthe coil 31 interfere with one another, thereby maintaining thecross-section of the bending portion 30 in a substantially circularshape. Also, the interference of the turn portions 31a with one anotherprevents the bending portion 30 from being bent only at one sectionthereof, thus ensuring a smooth bending.

In the above construction, the pair of strips 33 for limiting the coil31 are independent of each other, and are not received in the internalspace 32 of the coil 31. Therefore, the internal space 32 is notdivided, and can be effectively used, without any dead space existingtherein. As a result, limitations such as a limitation on the thicknessof the optical fiber bundles are relaxed as compared with theabove-mentioned conventional structure.

Other embodiments of the present invention will now be described. Thoseparts of these other embodiments corresponding respectively to those ofthe preceding embodiment are designated by identical reference numerals,respectively, and detailed explanation thereof will be omitted.

In an embodiment shown in FIG. 7, each adjacent support portions 33a ofeach strip 33 are disposed in contact with each other, and adjacent turnportions 31a of a coil 31 are spaced from each other a distance twicethe thickness of the strip 33. As a result, a pulling force applied bythe operating wire is not partially absorbed by a resilient compressionof the strips 33 in the axial direction of the coil 31, but is fullyused to bend the bending portion.

In the embodiment of FIG. 7, connecting portions 33b of the strip 33 areprojected considerably radially outwardly from an imaginary cylindricalsurface in which the center of the transverse cross-sectional area ofeach turn portion 31a of the coil 31 lies. With this arrangement, thebending as shown in FIG. 6 is possible. Each of the strips 33 isdisposed inside the coil 31, and the support portions 33a mainly supportthe inside sections of the turn portions 31a of the coil 31.

In the embodiment of FIG. 7, the turn portions 31a of the coil 31 arenot fixed to the respective support portions 33a of each strip 33. In anatural condition of the strip 33 in which the strip is not subjected toany force, the inner diameter of the support portion 33a is slightlysmaller than the diameter of the turn portion 31a, and the supportportion 33a is kept engaged with (that is, held in intimate contactwith) the turn portion 31a only by the resiliency of the support portion33a. The support portion 33a circumferentially extends around thetransverse cross-section of the turn portion 31a through an angleexceeding 180°. It is preferred that the opposite axial ends of eachstrip 33 be fixedly secured to the connecting tube at the distal end ofthe insertion portion and the cylindrical portion of the frame of therigid portion, respectively.

In an embodiment shown in FIG. 8, a pair of wires 55 of metal or a resinare used as limiting members. Each wire 55 cooperates with another wire56, extending straight in an axial direction of a coil 31, to limit anaxial compression of the coil 31. More specifically, the wire 55 iswound on about a half of an outer periphery of each turn portion 31a ofthe coil 31, and is folded or turned back around the wire 56, andfurther is wound on about a half of an outer periphery of the adjoiningturn portion 31a. In this manner, the wire 55 is engaged with all theturn portions 31a in the axial direction of the coil 31. The distancebetween each adjacent turn portions 31a of the coil 31 is substantiallyequal to the diameter of the wire 55. One ends of the wires 55 and 56are fixedly secured to the connecting tube at the distal end of theinsertion portion, and the other ends of these wires are fixedly securedto the cylindrical portion of the frame of the rigid portion.

In an embodiment shown in FIG. 9, a coil 31 can be bent in alldirections. More specifically, the coil 31 is divided into alternateregions M and N in its axial direction. Each region includes, forexample, five turn portions 31a. A pair of strips 33 are connectedrespectively to diametrically-opposite sections of the turn portions 31aof each region M which sections are spaced from each other in adirection X. Also, a pair of strips 33 are connected respectively todiametrically-opposite sections of the turn portions 31a of each regionN which sections are spaced from each other in a direction Y. Fouroperating wires (not shown) are passed through an internal space of thecoil 31. Two of the four operating wires are disposed indiametrically-opposite relation to each other in the direction X withrespect to the coil 31 whereas the other two operating wires aredisposed in diametrically-opposite relation to each other in thedirection Y with respect to the coil 31. When one of the former twooperating wires is pulled, the regions N of the coil 31 are bent in thedirection X, with the regions M of the coil 31 hardly deformed. When oneof the latter two operating wires is pulled, the regions M of the coil31 are bent in the direction Y, with the regions N of the coil 31 hardlydeformed. Thus, the coil 31 can be bent in four directions and hence alldirections.

An embodiment shown in FIG. 10 is similar to the embodiment of FIG. 9,but differs therefrom on the following points. Namely, a coil 31 hasregions L each interposed between adjacent regions M and N, the region Lincluding two turn portions 31a. Two support portions 33a, provided atone end of each of two strips 33 extending from the region M, areengaged respectively with the two turn portions 31a defining the regionL. Similarly, two support portions 33a, provided at one end of each oftwo strips 33 extending from the region N, are engaged respectively withthe two turn portions 31a defining the region L. Thus, the two strips 33extending from the region M and the two strips 33 extending from theregion N are engaged with the two turn portions 31a (defining the regionL) at four points spaced 90° from one another in the circumferentialdirection of the coil 31. Thus, the turn portions 31a of the region Mand the turn portions 31a of the region N are interconnected via theturn portions 31a of the region L and the strips 33. This arrangementprevents a relative radial displacement between the turn portions 31a ofthe region M and the turn portions 31a of the region N when any ofoperating wires 51 to 54 is pulled.

In an embodiment shown in FIGS. 11 to 13, instead of the coil 31 used inthe above embodiments, there is used a bellows 60 of metal which is thinand bendable, the bellows 60 being formed by an electroforming method.The bellows 60 is of a tubular shape having a circular transversecross-section, and has an internal space 61 therein. The bellows 60 hasfirst portions 60a radially outwardly bulged, and second portions 60bradially inwardly bulged. The first and second portions 60a and 60b arealternately arranged in the axial direction of the bellows 60, and theperipheral wall of the bellows 60 has a corrugated shape except for adistal end portion 60c and a proximal end portion of the bellows 60which are cylindrical. The cylindrical distal end portion 60c is fittedon and fixedly secured to the cylindrical portion 41b of the frame 41 ofthe rigid portion 40. The cylindrical proximal end portion (not shown)of the bellows 60 is connected to the distal end of the holder coil ofthe insertion portion via the connecting tube.

A pair of limitation members 69 of metal each in the form of a strip orelongated plate are mounted respectively on diametrically-oppositeportions of the outer periphery of the bellows 60 spaced from each otherin a direction X, the pair of limitation members 69 extending in theaxial direction of the bellows 60 over generally the entire lengththereof. One lateral edges of the pair of limitation members 69 opposedto each other are of a corrugated shape corresponding to the corrugatedshape of the outer peripheral surface of the bellows 60. This corrugatedlateral edge of each of the limitation members 69 has a series ofinsertion portions (projections) 69a spaced at equal intervals from oneanother along the length of the limitation member 69. The insertionportions 69a are fitted respectively in the second portions 60b of thebellows 60, and the first portions 60a of the bellows 60 are fittedrespectively in recesses each formed between each adjacent insertionportions 69a. Each of the limitation members 69 is fixedly secured byspot welding, an elastic adhesive, brazing or the like to the outerperipheral surface of the bellows 60 either at regions spaced along thelength thereof or over the entire length thereof. The limitation members69 limit the axial compression of the bellows 60, and allow the bellows60 to be bent only in a direction Y perpendicular to a plane in whichthe limitation members 69 lie. Operating wires 51 and 52 are passedthrough the internal space 61 of the bellows 60, and are spaced 90° fromthe limitation members 69 in the circumferential direction of thebellows 60, and are disposed in diametrically opposite relation in thedirection Y. A braid tube (not shown) is fitted around the bellows 60,and a tube is fitted around this braid tube. The use of such braid tubeand such tube may be omitted.

In the above construction, when one of the operating wires 51 and 52 ispulled, one side of the bellows 60 along which the pulled operating wireis disposed is axially contracted whereas the other side of the bellows60 disposed in diametrically opposite relation to the one side thereofis axially expanded. At this time, because the axial compression of thebellows 60 is limited by the limitation members 69, the overall lengthof the bellows 60 on the axis or centerline thereof is not changed. As aresult, the bellows 60 is bent toward the side of the pulled operatingwire. The purposes of the limitation members 69 are to positivelyconvert the pulling force of the operating wire 51, 52 into a force forbending the bellows 60, and also to allow the bellows 60 to be bent inthe intended direction.

An embodiment shown in FIGS. 14 to 16 is similar to the embodiment ofFIGS. 11 to 13 in that a bellows 60 is used, but differs therefrom inthat spherical pieces 62 of metal (hereinafter referred to as "metalball") are used as limitation means. Two rows of metal balls 62 arearranged over generally the entire length of the bellows 60, and morespecifically are arranged respectively along two imaginary straightlines which extend parallel to the axis of the bellows 60 and aredisposed respectively at diametrically-opposite portions of thecorrugated peripheral wall of the bellows 60. The metal balls 62 in eachrow are disposed alternately inside and outside of the corrugatedperipheral wall of the bellows 60. Those metal balls 62 disposed insidethe bellows 60 are fitted in and fixedly secured to first portions 60aof the bellows 60, respectively, and those metal balls 62 disposedoutside the bellows 60 are fitted in and fixedly secured to secondportions 60b of the bellows 60. The metal balls 62 are fixedly securedto the bellows 60 by spot welding, an elastic adhesive, brazing or thelike. The bellows 60 can not be axially expanded or contracted at thoseportions thereof to which the metal balls 62 are secured, and can beaxially expanded or contracted only at those portions thereof where themetal balls 62 are not attached. As a result, the bellows 60 can not bebent in a direction X (FIG. 16), and can be bent only in a direction Yperpendicular to a plane in which the two rows of metal balls 62 aredisposed.

Each row of metal balls 62 are disposed between a cylindrical surfaceinscribed in the bellows 60 and a cylindrical surface circumscribedabout the bellows 60, and therefore the use of the metal balls 62 doesnot increase the diameter of the bending portion.

An embodiment shown in FIGS. 17 and 18 is similar to the embodiments ofFIGS. 11 to 16 in that a bellows is used, but differs therefrom in thatthe bellows can be bent in all directions. More specifically, thebellows 60 has regions P and Q arranged alternately in the axialdirection of the bellows 60. At each of the regions P, two rows ofalternate first and second pieces 63 and 64 are arranged respectivelyalong two imaginary straight lines which extend parallel to the axis ofthe bellows 60 and are disposed respectively at diametrically-oppositeportions of the corrugated peripheral wall of the bellows 60 spaced fromeach other in a direction Y. At each of the regions Q, two rows ofalternate first and second pieces 63 and 64 are arranged respectivelyalong two imaginary straight lines which extend parallel to the axis ofthe bellows 60 and are disposed respectively at diametrically-oppositeportions of the corrugated peripheral wall of the bellows 60 spaced fromeach other in a direction X.

Each of the pieces 63 and 64 has one end portion which is rounded orsemi-spherical, and the other end portion has a rectangularcross-section. The first piece 63 is longer than the second piece 64.

The first pieces 63 are disposed inside the corrugated peripheral wallof the bellows 60, and their rounded one end portions are fitted in andfixedly secured to first portions 60a of the bellows 60, respectively.The other end portions of the first pieces 63 are projected radiallyinwardly beyond the inner peripheries of second portions 60b of thebellows 60. An insertion hole 63a is formed through each of theseprojected end portions, and extends in the axial direction of thebellows 60. The second pieces 64 are disposed outside the corrugatedperipheral wall of the bellows 60, and their rounded one end portionsare fitted in and fixedly secured to the second portions 60b of thebellows 60. The other ends of the second pieces 64 either coincide witha circumscribed cylindrical surface of the bellows 60 or disposedradially inwardly of this circumscribed cylindrical surface.

Four operating wires 51 to 54 are disposed in an internal space 61 ofthe bellows 60, and are passed through the insertion holes 63a of thefour rows of first pieces 63, respectively.

In the above construction, when one of the operating wires 51 and 52 ispulled, the bellows 60 can not be bent at the regions P, but can be bentat the regions Q in the direction Y (FIG. 18). When one of the operatingwires 53 and 54 is pulled, the bellows 60 can not be bent at the regionsQ, but can be bent at the regions P in the direction X (FIG. 18). Thus,the bellows 60 can be bent in all directions.

In this embodiment, since the operating wires 51 to 54 are guided by thefirst pieces 63, the optical fibers, the guide tubes and etc., receivedin the internal space 61 of the bellows 60 are not pressed by theoperating wires when the bellows 60 is bent.

An embodiment shown in FIGS. 19 and 20 is similar to the embodiment ofFIGS. 14 to 16, but differs therefrom on the following points. Two rowsof insertion holes 65 are formed respectively throughdiametrically-opposite portions of corrugations of a peripheral wall ofa bellows 60, the two rows of insertion holes 65 being disposedrespectively on two straight lines parallel to the axis of the bellows60. Operating wires 51 and 52 are passed through the two rows ofinsertion holes 65, respectively.

In an embodiment shown in FIG. 21, two rows of notches 66 are formedrespectively in diametrically-opposite sections of outer peripheries offirst portions 60a of a bellows 60, the two rows of notches 66 beingdisposed respectively on two straight lines parallel to the axis of thebellows 60. Operating wires 51 and 52 are received in the two rows ofnotches 66, respectively.

In the embodiments shown in FIGS. 19 and 20 and FIG. 21, since theoperating wires 51 and 52 are not disposed in an internal space 61 ofthe bellows 60, the internal space 61 offers a greater area or spaceused for receiving the associated parts such as optical fibers. Andbesides, since the operating wires 51 and 52 are not moved into theinternal space 61 when the bellows 60 is bent, the optical fibers, theguide tubes and etc., are not pressed by the operating wires.

The present invention is not to be restricted to the above embodiments,and various modifications can be made.

For example, the limitation members 61 and the pieces 62 to 64 may bemade of an elastic material such as relatively rigid rubber.

The use of only one operating wire is possible, in which case thebending portion can be bent in one direction.

The present invention can be applied to the endoscope of the type inwhich the thicknesses or diameters of the insertion portion and thebending portion are very small, and further the present invention can beapplied to a medical catheter.

What is claimed is:
 1. A bending device comprising(a) a bellows havingan internal space therein, and having a corrugated peripheral walldefined by first and second portions arranged alternately in a directionof an axis of said bellows, said first portions being bulged radiallyoutwardly whereas said second portions are bulged radially inwardly; (b)operating wire means for bending said bellows, said operating wire meanshaving a proximal end portion adapted to receive an operating force,said operating wire means having a distal end portion substantiallyfixed to a distal end portion of said bellows; (c) at least one pair ofindependent limitation means for limiting an axial compression of saidbellows, said pair of limitation means being arranged in an axialdirection of said bellows and mounted respectively ondiametrically-opposite portions of said peripheral wall of said bellows,each of said pair of limitation means including insertion portionsfitted respectively in at least one of said first portions and secondportions of said bellows, and said bellows being bendable in a directionperpendicular to a plane in which said pair of limitation means aredisposed, and wherein each of said limitation means comprises a row ofalternate first and second pieces serving as said insertion portions,said first pieces being disposed inside said peripheral wall of saidbellows, said second pieces being disposed outside said peripheral wallof said bellows, said first pieces being fitted in and fixedly securedto said first portions of said bellows, respectively, and said secondpieces being fitted in and fixedly secured to said second portions ofsaid bellows, respectively.
 2. A bending device according to claim 1, inwhich each of said first and second pieces has a spherical shape.
 3. Abending device comprising(a) a bellows having an internal space therein,and having a corrugated peripheral wall defined by first and secondportions arranged alternately in a direction of an axis of said bellows,said first portions being bulged radially outwardly whereas said secondportions are bulged radially inwardly; (b) operating wire means forbending said bellows, said operating wire means having a proximal endportion adapted to receive an operating force, said operating wire meanshaving a distal end portion substantially fixed to a distal end portionof said bellows; (c) at least one pair of independent limitation meansfor limiting an axial compression of said bellows, said pair oflimitation means being arranged in an axial direction of said bellowsand mounted respectively on diametrically-opposite portions of saidperipheral wall of said bellows, each of said pair of limitation meansincluding insertion portions fitted respectively in at least one of saidfirst portions and second portions of said bellows, and said bellowsbeing bendable in a direction perpendicular to a plane in which saidpair of limitation means are disposed, and wherein a row of insertionholes are formed through the corrugations of said peripheral wall ofsaid bellows, said row of insertion holes being disposed on a straightline parallel to the axis of said bellows, and said operating wire meansbeing passed through said row of insertion holes.